@derek-m turns on at 21C off at 22C, its came on at 1.30pm today will probably hit 22C around 6.30 so 5 hours run time no cycling at 1kwh.

Once its off early evening it won't come on again till the early hours then off at 5.30 or when it hits 22C then the cycle repeats.

Thanks Gary, it would appear that you ave found the sweet spot for how to operate your system efficiently. It sounds similar to a suggestion that I made probably over 2 years ago, as a possible method of improving efficiency by boosting indoor temperatures during the warmer daytime period when the heat pump would probably operate more efficiently. Since then the possible problem of cycling has become apparent, and it would appear that your method would appear to solve both issues.

Have you considered a more controlled method, so that you can avoid the heat pump from operating during peak periods if at all possible?

@derek-m At current mild OAT its all run from battery charged off-peak supplemented with solar if required, I run house/heatpump/charge battery from the grid 23.30-05.30.

Then run everything from battery from 05.30 to 23.30 or until it runs out, that only really happens when OAT drops to 0C.

Last year I imported 850kwh from the grid at peak periods, that was all during the heating season Nov-Mar.  I looked at another battery but even my man maths can't justify it.

Hi JakeT, I agree with all the replies. My flow rate is 19 l/min, however I have all UFH and no buffer tank. I also have local pumps for the UFH, and I have the living room pump on max, others on min. My cop is 2.3-4.3, 3.2 average, for this January. I use Advanced Auto Adaptation with a mitsubishi wireless thermostat in the living room. I run my hp 24x7, but programmed at the FTC (tricky) for 21C from 1400 hrs, 20C from 2200 hrs which usually switches off the HP for 3-5 hours depending on the outside temperature. I think you can only program a setback on Room Temperature or AAA mode. I find AAA very good, with almost no cycling, and I don't have to touch it, unlike the WC which I used to use before I installed the Mitsubishi wireless thermostat. It also switches itself off when the sun heats the living room. With WC, it''s true 32C at 15C outside is probably as low as you can go without cycling, but you need to have enough flow in enough areas to use the lowest heat output of the HP to avoid it cycling off. Cycling reduces the cop because the hp is less efficient restarting, puts cooler water through your system and slows down your heating, and worst of all can wear out your compressor prematurely. You said your hot water comes from the bottom of the tank! - that is never done. The temperature to heat it to depends on where the thermostat is. Ours is low, and we don't use much hot water, so 47C is ok for us. Usually it would be higher. In the Winter I have it on Normal, not ECO, so the room heating is not off for too long. Good luck!

Just to mention, if your Ecodan has sufficient spare capacity you could try running in one of the two Quet Mode settings. 

In addition to being quieter,  it also limits maximum compressor speed. I've found this can help to reduce the ramp rate and hence lengthen the time between cycles.  It should also mean the compressor doesn't work as hard.

When it's subzero for prolonged winter periods we switch back to normal (full) power.

Obviously feasibility all depends on how much capacity margin exists in each  installation.

Quiet Mode is in Heat Pump settings in the Service menu (on FTC6).

Hope this helps.

@skd That is a good point but it is only on FTC 6 it’s not on FTC5 or at least I don’t have it on my FTC5

Ah okay.  Sorry it wasn't any help.

Thanks for all the replies @sliderule I have tried AAA as I have FTC6 however this ramps the flow temperature up a lot and I thought this was the most important aspect of efficiency?

I set AAA last night and can see today with a similar OAT I am not cycling but the flow temperature is running at 40c compared to the 31c weather comp wanted 

 @skd do you think setting quiet mode might help with this ? 

The house feels lovely on WC and never varies just the excessive cycling is not good 

@rich you have to leave AA for a good while.  Days/weeks while it works itself out.  A few hours isn't enough time.

I expect AA prioritises room temperature over cop, which most customers would want. Perhaps it takes time to stabilise. Last night our OAT was 3C, flow 38C (would have been 37C on my previous WC curve), return 34C, room target 20C (setback from 21C) all steady, no cycling. I have spent some time balancing the rooms to optimise costs without cycling, as I blame that for breakdowns of my 13 year old Ecodan which I have had to replace. Heat exchanger leaks/ refrigerant loss twice then compressor failure. It had run 22000 hours with 95000 compressor starts. I didn't realise it was cycling for some years until we got a Smart Meter. It was also oversized, especially as we only heat half the house! So I am delighted that it doesn't cycle on AA, and I don't have to constantly fiddle with the WC curve. And also that it switches off and has a rest when it can. I only notice ramping up after a lot of sun in the living room, and I am working on smoothing that out. I will try the Quiet Mode.

@sliderule yes Quiet Mode is definitely worth a try for comparison.  According to Mitsubishi techs it works by simply limiting the max compressor speed. It shouldn't reduce max flow temperature unless OAT is low enough that it can't meet the heat demand,  and then flow temp basically flatlines.  That’s when I switch back to Normal, eg when it's subzero continuously, and full output resumes immediately.

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 @skd do you think setting quiet mode might help with this ? 

Sorry Rich I missed your question earlier.  Please see my post just before this one, does that help at all?